Percussive Tool Control Method for Cold Startup Reliability
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Solution Overview
Problem
Percussive hand-held power tools, such as pneumatic percussion drills, face challenges in starting reliably in cold environments due to the striking mechanism being cold, which affects its optimal operating temperature and performance.
Innovation Solution
A control method that detects the temperature using a sensor and adjusts the repetition rate of the electropneumatic striking mechanism, increasing it rapidly when the temperature is above a limiting value and gradually when below, to ensure reliable startup and efficient operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the repetition rate is rapidly increased from idle to setpoint value, then the productivity is improved, but the reliability deteriorates in cold environments
Solution Approach 1:
The patent applies dynamics by making the acceleration of the repetition rate adaptive based on temperature conditions. The control system dynamically adjusts the acceleration parameter: using high acceleration (first acceleration) when temperature is above the limiting temperature for rapid productivity increase, and using low acceleration (second acceleration less than 1/10 of the first) when temperature is below the limiting temperature to ensure reliable startup. This dynamic adaptation resolves the contradiction between productivity and reliability across different thermal conditions.
Solution Approach 2:
The patent changes the operational parameters of the striking mechanism based on temperature detection. A temperature sensor detects the current temperature, and the control system modifies the repetition rate acceleration parameter accordingly. When temperature exceeds the limiting temperature, the system uses a first acceleration value for rapid response. When temperature is below the limiting temperature, it uses a second acceleration value (less than 1/10 of the first) to gradually warm up the mechanism, ensuring reliable operation. This parameter adaptation resolves the contradiction between fast startup and reliable startup in cold conditions.
2Loss of time
If the repetition rate is rapidly increased, then the time to reach optimal performance is reduced, but the risk of malfunction increases in cold conditions
Solution Approach 1:
The system dynamically adapts the startup profile based on detected temperature. Above the limiting temperature, the repetition rate increases rapidly with first acceleration, minimizing startup time. Below the limiting temperature, the system switches to a gradual increase with second acceleration (less than 1/10 of the first), preventing malfunction while still achieving optimal performance. This dynamic behavior resolves the time-reliability contradiction.
Solution Approach 2:
The patent implements feedback through a temperature sensor that continuously monitors the striking mechanism temperature. Based on this feedback, the control system adjusts the repetition rate acceleration: using first acceleration when temperature is above the limiting temperature for quick response, and second acceleration (less than 1/10 of the first) when below the limiting temperature to ensure reliable operation. This feedback mechanism resolves the contradiction between minimizing startup time and preventing cold-temperature malfunctions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This method allows for quick and reliable activation of the striking mechanism, ensuring efficient operation and reducing the duration to reach optimal performance, even in cold conditions.
Implementation Method 1
detecting a temperature using a temperature sensor
Implementation Method 2
a striker coupled to the exciter via a pneumatic chamber is also moved
Data Source
AI summary
A control method for a percussive hand-held power tool (1) includes the steps: detecting a switching state of an operating button (12), detecting a temperature T using a temperature sensor (22), activating an electropneumatic striking mechanism (5) in response to an actuation of the operating button (12), an exciter (13) of the electropneumatic striking mechanism (5) being moved forward and backward along a working axis (3) at a repetition rate R, whereby a striker (14) coupled to the exciter (13) via a pneumatic chamber (16) is also moved. If the temperature T is greater than a limiting temperature Tc, the repetition rate R is continuously increased from idle up to a setpoint value (21). A duration until reaching the setpoint value (21) is less than 10 cycles. If the temperature T is less than the limiting temperature Tc, a duration until reaching the setpoint value (21) is greater than 200 cycles.